Effects of isoproterenol on Na+ and K+ transport in frog skin epithelium.
The acute effects of isoproterenol on Na+ extrusion and K+ uptake across the basolateral membrane of the isolated epithelium of the frog skin were examined. A chloride-free sulfate Ringer was used in all experiments. Isoproterenol caused an approximate doubling of the short-circuit current (Isc) and the transepithelial Na+ flux (J13Na). Isc remained equal to J13Na. After isoproterenol treatment, ouabain inhibited Isc and J13Na in a manner similar to control tissues. Ouabain-sensitive K+ uptake was also measured under comparable conditions. In two sets of experiments, K+ uptake was increased on average by only 5 and 17 percent after isoproterenol treatment. Thus, isoproterenol caused Na+ flux to more than double while K+ uptake increased by only 5-17%. These data cannot be readily accounted for by a pump with a fixed Na+/K+ exchange ratio.
Cox
T C
TC
Department of Physiology, School of Medicine, Southern Illinois University, Carbondale 62901.
Grieme
M
M
Woods
R
R
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D004848:Epithelium / Q000378:metabolism / Q000502:physiology; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D011188:Potassium / Q000378:metabolism*; D011894:Rana pipiens; D012867:Skin / Q000378:metabolism*; D012879:Skin Physiological Phenomena; D012964:Sodium / Q000378:metabolism*
D012964:Sodium; D007545:Isoproterenol; D011188:Potassium